The patch titled
Subject: kasan, arm64: don't tag executable vmalloc allocations
has been removed from the -mm tree. Its filename was
kasan-arm64-dont-tag-executable-vmalloc-allocations.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan, arm64: don't tag executable vmalloc allocations
Besides asking vmalloc memory to be executable via the prot argument of
__vmalloc_node_range() (see the previous patch), the kernel can skip that
bit and instead mark memory as executable via set_memory_x().
Once tag-based KASAN modes start tagging vmalloc allocations, executing
code from such allocations will lead to the PC register getting a tag,
which is not tolerated by the kernel.
Generic kernel code typically allocates memory via module_alloc() if it
intends to mark memory as executable. (On arm64 module_alloc() uses
__vmalloc_node_range() without setting the executable bit).
Thus, reset pointer tags of pointers returned from module_alloc().
However, on arm64 there's an exception: the eBPF subsystem. Instead of
using module_alloc(), it uses vmalloc() (via bpf_jit_alloc_exec()) to
allocate its JIT region.
Thus, reset pointer tags of pointers returned from bpf_jit_alloc_exec().
Resetting tags for these pointers results in untagged pointers being
passed to set_memory_x(). This causes conflicts in arithmetic checks in
change_memory_common(), as vm_struct->addr pointer returned by
find_vm_area() is tagged.
Reset pointer tag of find_vm_area(addr)->addr in change_memory_common().
Link: https://lkml.kernel.org/r/b7b2595423340cd7d76b770e5d519acf3b72f0ab.1643047180.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Acked-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/module.c | 3 ++-
arch/arm64/mm/pageattr.c | 2 +-
arch/arm64/net/bpf_jit_comp.c | 3 ++-
3 files changed, 5 insertions(+), 3 deletions(-)
--- a/arch/arm64/kernel/module.c~kasan-arm64-dont-tag-executable-vmalloc-allocations
+++ a/arch/arm64/kernel/module.c
@@ -63,7 +63,8 @@ void *module_alloc(unsigned long size)
return NULL;
}
- return p;
+ /* Memory is intended to be executable, reset the pointer tag. */
+ return kasan_reset_tag(p);
}
enum aarch64_reloc_op {
--- a/arch/arm64/mm/pageattr.c~kasan-arm64-dont-tag-executable-vmalloc-allocations
+++ a/arch/arm64/mm/pageattr.c
@@ -85,7 +85,7 @@ static int change_memory_common(unsigned
*/
area = find_vm_area((void *)addr);
if (!area ||
- end > (unsigned long)area->addr + area->size ||
+ end > (unsigned long)kasan_reset_tag(area->addr) + area->size ||
!(area->flags & VM_ALLOC))
return -EINVAL;
--- a/arch/arm64/net/bpf_jit_comp.c~kasan-arm64-dont-tag-executable-vmalloc-allocations
+++ a/arch/arm64/net/bpf_jit_comp.c
@@ -1304,7 +1304,8 @@ u64 bpf_jit_alloc_exec_limit(void)
void *bpf_jit_alloc_exec(unsigned long size)
{
- return vmalloc(size);
+ /* Memory is intended to be executable, reset the pointer tag. */
+ return kasan_reset_tag(vmalloc(size));
}
void bpf_jit_free_exec(void *addr)
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
stacktrace-add-interface-based-on-shadow-call-stack.patch
arm64-scs-save-scs_sp-values-per-cpu-when-switching-stacks.patch
arm64-implement-stack_trace_save_shadow.patch
kasan-use-stack_trace_save_shadow.patch
